a list of candidate mvs to check before starting the iterative search. If one of the candidates is close to the optimal mv, then it takes fewer iterations. And it increases the chance that we find the optimal mv.

< x and y coordinates of the best motion vector. i.e. the difference between the position of the block currently being encoded and the position of the block chosen to predict it from.

< the score (cmp + penalty) of any given mv

< the best value of d, i.e. the score corresponding to the mv stored in best[].